[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] xen/arm: smmuv1: remove iommu group when deassign a device
Hi, On 27/04/2022 17:15, Rahul Singh wrote: When a device is deassigned from the domain it is required to remove the iommu group. This read wrong to me. We should not need to re-create the IOMMU group (and call arm_smmu_add_device()) every time a device is re-assigned. If we don't remove the group, the next time when we assign a device, SME and S2CR will not be setup correctly for the device because of that SMMU fault will be observed. I think this is a bug fix for 0435784cc75dcfef3b5f59c29deb1dbb84265ddb. If so, please add a Fixes tag. Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx> --- xen/drivers/passthrough/arm/smmu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c index 5cacb2dd99..9a31c332d0 100644 --- a/xen/drivers/passthrough/arm/smmu.c +++ b/xen/drivers/passthrough/arm/smmu.c @@ -1690,6 +1690,8 @@ static void arm_smmu_detach_dev(struct iommu_domain *domain, struct device *dev) if (cfg) arm_smmu_master_free_smes(cfg);+ iommu_group_put(dev_iommu_group(dev));+ dev_iommu_group(dev) = NULL; } The goal of arm_smmu_detach_dev() is to revert the change made in arm_smmu_attach_dev(). But looking at the code, neither the IOMMU group nor the smes are allocated in arm_smmu_attach_dev(). Are the SMES meant to be re-allocated everytime we assign to a different domain? If yes, the allocation should be done in arm_smmu_attach_dev(). If not, then we should not free the SMES hereIIUC, the SMES have to be re-allocated every time a device is assigned. Therefore, I think we should move the call to arm_smmu_master_alloc_smes() out of the detach callback and in a helper that would be used when removing a device (not yet supported by Xen). Cheers, -- Julien Grall
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |